The object of the present invention is the crosslinking of non-fluorinated epoxy resins, of known type, with fluorinated polyfunctional crosslinking agents, characterized by a chain formed by oxyperfluoroalkylene units, in order to obtain crosslinked resins, endowed with improved characteristics as compared to the corresponding non fluorinated resins of known type.
The specific characteristics of the crosslinked resins obtained according to the invention are:
Surface properties which give oil- and water-repellence, as well as a low friction coefficient to the product; PA0 Resistance to hydrolysis and minimum water absorption; PA0 Resistance to solvents; PA0 Advantageous dielectric characteristics, in particular as relates to the dielectric constant and the volume resistivity; PA0 Enhanced flexibility and high impact resistance. PA0 R.sub.f represents a chain constituted by oxyperfluoroalkylene units, having an average molecular weight of from 400 to 8,000; PA0 Z can be, when present, one or more of groups of type: --CONH--, --CF.sub.2 --, --CH.sub.2 O--, --CH.sub.2 OCH.sub.2 --, --O--, --CH.sub.2 OSO.sub.2 --; PA0 n is an integer equal to 0 or 1; PA0 R is a divalent C.sub.1 -C.sub.12 aliphatic, or cycloaliphatic, or aromatic radical; in particular, it can be: --(CH.sub.2).sub.1-12 ; ##STR9## --(C.sub.a H.sub.2a O).sub.b --wherein: a=1-4; b=1-10; X and Y, equal to, or different, from each other, represent functional groups suitable to react with the epoxy and/or hydroxy groups present in the starting resin, and are, e.g.: PA0 t and t.sub.1 are integers of from 1 to 3. PA0 (I) (CF.sub.2 CF.sub.2 O), (CF.sub.2 O), said units being randomly distributed along the perfluoropolyether chain; PA0 (II) ##STR13## (CFXO), with X=F or CF.sub.3, said units being randomly distributed along the perfluoropolyether chain; PA0 (III) (CF.sub.2 CF.sub.2 O), ##STR14## (CFXO), with X=F or CF.sub.3, with said units being randomly distributed along the perfluoropolyether chain; PA0 (IV) ##STR15## (V) (CH.sub.2 CF.sub.2 CF.sub.2 O); (VI) (CF.sub.2 CF.sub.2 CF.sub.2 O); PA0 (VII) --(O--CF.sub.2 --CF.sub.2 --CH.sub.2).sub.p --O--R'.sub.f --O--(CH.sub.2 --CF.sub.2 --CF.sub.2 --O).sub.q -- wherein R'.sub.f is a fluoroalkylene group, p and q are integers comprised within the range of from 0 to 200, and p+q is at least 1; PA0 (VIII) ##STR16## wherein R".sub.f is a fluoroalkylene group, n' is either 0 or 1, a and b are integers, and a+b is at least 1; PA0 (IX) (CF.sub.2 CF.sub.2 O). PA0 (X) ##STR17## wherein R.sub.f '" is F or a perfluoroalkyl group and n" is at least 8. PA0 a high chemical resistance, high resistance to hydrolysis and high resistance to atmospheric agents; PA0 high heat resistance; PA0 a very low refractive index; PA0 a considerably dimensional stability; PA0 a low wettability; PA0 a high crosslinking degree; PA0 self-lubricating properties; PA0 excellent mechanical properties; PA0 water-repellence, oil-repellence; PA0 flame-proofing properties; PA0 a low dielectric constant; PA0 a high heat-dissipation coefficient.